Leaving the battlefield (via running out of a particular range, Escape, Warp, etc) will remove you from the battlefield.

All mobs spawned will spawn as aggressive to the person who initiated the battlefield. However, hate is not immediately established on spawn, thus allowing particular tanking strategies to be employed.

Rewards:

Rewards are broken into 3 categories:

Experience

Augmented Item

General Loot

If the boss mob is initially killed, only the chest with an Augmented Item will appear, and the additional mobs will despawn. Killing the additional mobs will increase the rewards as follows:

Your display of Prowess in battle has earned you an experience bonus as a reward!

An additional chest will spawn. This chest carries a set amount of points that is divided amongst the number of people participating. Points rewarded caps out depending on the level of the fight.

Your display of Prowess in battle has earned you a superior augment as a reward!

The Augmented Item chest holds an Augmented Item with more potent Augments than if you just killed the boss mob.

Your display of Prowess in battle has earned you an increase in gil as a reward!

An additional chest will spawn. This chest carries loot that can be sold.